Scientists have discovered a lake of liquid water on Mars hidden beneath multiple layers of dust and ice, according to a paper published in Science on Wednesday.
It has long been suspected that the Red Planet is not as dry and arid as it looks. Over the years, spacecrafts and rovers have uncovered evidence of its watery past. …

"Scientists led by Roberto Orosei examined that data between May 2012 and December 2015 and found that there was a very sharp change in the radar signals, when looking at the area, which was found 1.5km beneath the surface.

The researchers spent two years ensuring that the data wasn’t the result of some other effect – eventually ruling out every possible explanation apart from liquid water of some kind."

I assume that after they'd finished their examination of the data, it was given to other teams of scientists who tried to tear the conclusions apart. Only now do we get some kind of concensus opinion.

Compare this approach to that of politicians who will have some kind of idea or dream and then wake up and tell you that it's true and that anyone who disagrees with them is a fool or worse.

Re: That conclusion seems a bit fast to me

"Compare this approach to that of politicians who will have some kind of idea or dream and then wake up and tell you that it's true and that anyone who disagrees with them is a fool or worse."

Scientists deal with facts. Politicians deal with people, especially those who vote. People are slippery and evasive about getting others to pay for their needs; and politicians truly represent the people.

Politics is not as easy as it looks, and we are entitled to blame the voters (other people, of course).

Re: That conclusion seems a bit fast to me

"But we like The Register that way, right?"

Actually, no. I mostly enjoy the well-placed snark as much as the next guy, but prefer the actual information to stay as factually correct as possible. Admittedly this specific one is a very subjective example, but I for one was left with the impression of having read "ok guys, this time we found water for realsies, the matter is conclusively settled, full stop" when what the researchers wrote was merely "we found something consistent with the presence of liquid water and we have no idea what else could cause it". That's very, very far from "we found something that we know can be exclusively and only caused by presence of liquid water". And I don't appreciate needing to read the whole original source material just to untangle what the factual information I'm reading about is supposed to actually be.

Re: That conclusion seems a bit fast to me - also for the reaserchers

Re: That conclusion seems a bit fast to me

To be fair, the paper actually is quite definite, the abstract says;

Quantitative analysis of the radar signals shows that this bright feature has high relative dielectric permittivity (>15), matching that of water-bearing materials. We interpret this feature as a stable body of liquid water on Mars..

However it's not as if they jumped to that conclusion, they didn't just see a bright patch on an image and say "yep, that's water". Reading the paper to understand how they reached their conclusions is definitely warranted before criticising those conclusions. I have only skimmed it, but is seems pretty sound to me.

Re: That conclusion seems a bit fast to me

Well, there is plenty of Earth-based experience to back it up. Back in the 1980s, UK researchers (mainly at Scott Polar Research Institute) found similar evidence of lakes beneath the Antarctic Ice Cap. Lake Vostok was the big one, but many more lake candidates were identified. Of course, at the time the possibility of actually verifying that they were lake using drilling techniques was science-fiction! But there are plenty of ways of checking that the bright reflections are from a water layer:

1) Is the top surface smooth compared with surrounding areas?

2) Is the dielectric constant estimated from the strength of the echo compatible with water?

3) Is the combination of pressure (derived from the thickness of the ice column) and temperature (derived from knowledge of surface temperature plus estimates of geothermal heat flux) within the liquid part of water's phase diagram?

4) Is there a surface expression of the lake (not found until 1996 by SAR imaging)

Since then at least one of these lakes has been drilled and they are water bodies.

Finally, there's the question of what else could it be? It looks like water, it behaves like water and it's beneath a 2km column of (mostly) water!

I guess it's possible... what the probability actually is though. The other story about the dust coming from one giant structure and being rather deep across the planet might have buried any water. Who knows... we need a long drill on the next explorer.

Not so much a lake

"matching water or water-rich sediments", said the man in charge.

OK, so - if it were salt water like say the Dead Sea then the sand and stuff would sink down through it to the bottom, either lifting the water layer higher until it reached the surface, or simply becoming a layer of "water-rich sediments" in its own right. Underground lakes can exist under solid rock, as in Derbyshire's Speedwell Caverns, or under ice as in Antarctica, but not under soft sandy sediments.

Yes, the radar returns are compatible with a lake, but the rest of the geophysics certainly is not. It's like water-bearing sand/rock strata anywhere, and we don't call those "lakes".

I saw this first on the bbc news site, the comments there where astonishing, religion was key, spending money on science was a waste (wonder how they got computers to right on) brexit was a key topic.

Glad to come back to the register for some sensible (mostly) debate.

On topic, proper science at work, let’s have more of this. Finding liquid water in two locations means the prospect of more to come, and if there are microbes it will be more intelligent than the bbc commenters

Don't you mean added salts lower the FREEZING point instead of MELTING point? The lower the freezing point, the lower temp at which it remains a liquid. In other words, if you lower the melting point, ice would melt -5C instead of 0C. OR do you Brits just have weird ways to say things?

Re: Nope

It's even more complicated than that. When a liquid freezes, it usually precipitates out some or all of the solutes, which is why if you freeze sea water you get relatively fresh water ice cubes. If you have a liquid with a solute content, its freezing point is depressed, i.e. the temperature at which ice forms. However, once formed, the ice won't melt until it reaches the temperature at which the pure liquid melts. So for water ice which behaves like this, freezing point depression is correct and melting point is not.

The phase diagrams for metal alloys are even more complicated, such as the aluminium alloys in which copper can precipitate out after the metal has solidified.

tl;dr just reproduce what the scientists actually said and then if someone says you're wrong, refer them to the original paper. (The CMA defence.)